Automatic door operator



May 16, 1967 R. M. L OFTUS AUTOMATI C DOOR OPERATOR Filed Feb. 17, 1966 PUMP QUANTITY OUTPUTE INVENTOR RQBERT M. LoFTUs My WwM/a A i. B--T-c-+-- D -4 BY l ATTORNEYS United grates This is a continuation-in-part of application Serial No. 368,817, filed May 20, 1964.

This invention relates to a fluid operator system and particularly to such a system for use in the powering of doors in the door opening and closing cycle. The inve-ntion is especially applicable to swinging doors and one of its objects is to provide a fluid operator system of cornpact size and minimum heat generation.

It is a further object of this invention to provide a novel fluid operator system for automatic doors incorporating a fluid supply pump which operates during each door opening movement and cooperates with an -auxiliary accumulator for powering the doors to the open position. Included in this object is the provision of an arrangement for automatically recharging the accumulator during each door opening movement whereby it is conditioned for the next subsequent door opening movement.

Another object of this invention is to provide an improved hydraulic operator system providing for the hydraulic damping of the door during its return to closed position and for minimizing the hydraulic fluid leakage during the power stroke of the operator.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a schematic representation of a hydraulic door operator system depicting this invention;

FIG. 2 is a fragmentary and diagrammatic view of a hydraulic power operator illustrating the unique bypass control valve of this invention; and

FIG. 3 is a graph illustrating the fluid requirements of the system of FIG. 1 during a typical door opening movement Referring now to the drawings, in which like numerals indicate like parts throughout the several views, a pair of swinging doors of the type for which the fluid operator system of this invention is particularly designed are denoted generally by the numerals and are hung for pivotable movement adjacent their remote edges in a conventional manner.

Each of the doors 10 is provided with a fluid power operator 12 for powering the door during its opening and closing movement and, as shown in FIG. l, the power operator for each door is mounted in a recess in the threshold of the door with the output spindle 14 of each operator forming the bottom pivot of the door.

Referring now particularly to FIG. 2, each of the operators 12 is provided with a pair of pistons 16 and 18 which are mounted in separate cylinders and 22, respectively, in cylinder block 24. Each of the pistons 16, 18 are connected to the spindle 14 thorugh crank arms 26, 28, respectively, so that the movement of one of the pistons automatically causes the movement of the other. Each of the cylinders 20, 22 is provided with an inlet port 30, with the port 30 for the cylinder 22 shown las being closed by a plug 32 and the port 30 for the cylinder 20 being connected by a coupling nipple 36 and tubing 34 to a manifold 40. Coupling nipple 36 is provided atent O 3,319,386 Patented May 16, 1967 ICC with a one-way valve 38 which prevents the discharge of hydraulic uid from the interior of the cylinder 20.

Piston 16 is provided with a biasing or closing spring 44 which opposes the movement of the piston 16 during the power stroke of the piston and returns the piston to a neutral position after the power stroke, -at which time the door is in its normal or closed position.

With the operator connected, as shown in FIG. 2, the piston 16 serves as a power piston during the power stroke of the operator and moves to the left as viewed in FIG. 2 against the bias of its associated spring 44 (shown diagrammatically) it being understood that the one-Way valve 43 in the piston 16 is closed by the pressurized fluid entering the cylinder 20. In such operation, piston 18 moves to the right and serves as a checking piston to hydraulically damp the movement of the spindle 14. Because of the hydraulic fluid trapped in the cylinder 22, the oneway check valve 43 of piston 18 is also seated.

To provide for the discharge of hydraulic fluid trapped in checking cylinder 22 under such conditions, there are provided bypass needle valves 42' which are adjustable to accommodate the desired rates of movement of the spindie 14 during diiferent portions of door opening movement. The needle valves 42 provide communication between the interior of the cylinder 22 and the passageway 45 in the cylinder block, the end of which discharges through a port 46 into the interior of the housing of the operator 12.

Cylinder 20 is likewise provided with bypass needle valves 42 so that the piston 16 may serve as the checking piston during the closing of the door under the linfluence of the spring 44. The presence of these needle valves 42 in cylinder 20, however, normally results in undesired leakage of pressurized iiuid during the power stroke of the piston 16 and one of the important features of this invention is to provide a bypass control valve arrangement which is automatically operable to substantially eliminate such leakage from the bypass needle valves 42 during the power stroke of piston 16.

As indicated above, the power operator 12 illustrated in FIG. 2 is diagrammatical in nature. For a more complete description of such a power operator 12, reference is made to US. Patent 2,911,210 which issued on November 3, 1959, on an invention of Harold W. Ferguson and is entitled Hydraulic Door Operators.

The bypass control valve 50 utilized in this invention is shown as being mounted on cylinder block 24 to receive the fluid discharge from the outlet port 48 of passageway 47 through needle valve 42 of cylinder 20. Bypass control valve Sti is shown as being sealed to the outlet port 48 by a resilient O-ring 49.

The bypass control valve 50 is -a tubular member having an axial bo-re 52 of uniform diameter which receives a spool valve 54 for reciprocable movement therein. A biasing spring 56 urges the spool valve in one direction against the stop 5,8, which positions the spool valve so that the necked portion 60 thereof is aligned with inlet opening 62 and outlet opening 64 in the side walls of the valve 50. The inlet opening 62 communicates with the outlet port 48 of the passageway 47 of cylinder 20 so that when the spool valve 54 is in the position shown (as when the piston 16 is moving in the door closing direction under the inuence of its spring 44) the uid trapped in the cylinder 20 is discharged past the needle valves 42 directly into the housing of the operator to damp the movement of the piston.

However, when pressurized uid is admitted to manifold 40 to initiate the power stroke of piston 16 it is also fed into the end of bypass control valve 50 through tube 66 to urge the spool valve 54 against the bias of spring 56. Because the areas of the two enlarged ends of spool valve 54 are equal, any leakage past bypass valves 42 of cylinder entering the bypass control valve 50' through opening 62 produces equal and oppositely directed forces on the spool valve 54 and thus does not affect the biasing forces on the spool valve 54.

The spool valve 54 is provided with a stop 68 for limiting the movement of the spool valve so that the enlarged end of the spool valve 54 is positioned toseal off the inlet and outlet ports 62, 64, respectively, to prevent leakage past the bypass valves 42 during the power stroke. A drain port 69 is provided in the wall of the bypass control valve so that fluid is not trapped in the cavity for spring 56.

It will be readily apparent that while FIG. 2 diagrammatically illustrates the operator connected for right-hand operation, it could be readily adapted for left-hand operation by connecting supply tube 34 to inlet port 30 of cylinder 22 and applying the plug 32 to the inlet port 30 of cylinder 20 and reversing the bypass control valve 5) so that inlet port 62 thereof is in communication with eX- haust port 46 of passageway 45 for cylinder 22. For left hand operation, the return spring 44 associated with piston 16 (diagrammatically illustrated for right hand operation) woud be rendered ineffective and a similar spring 44 associated with piston 18 rendered effective as more fully described in the aforesaid U.S. Patent 2,911,210.

For an understanding of the operation of the power operator system of this invention refer to FIG. 1. A control switch, which may be any conventional switch such as a pedestrian operated carpet switch, is indicated by numeral 74). Closing the control switch 70 energizes the solenoid valves 72, 74 and relay switch 76 to energize the drive motor 78 for the positive displacement gear-type pump 80 to deliver pressurized uid through tubing 82 to the operators 12 thereby initiating the power stroke of the two power operators. The delivery of pressurized fluid to tubing 82 also operates the bypass control valves 50 for each of the operators to close outlet port 64 to prevent leakage of hydraulic fluid past the bypass valves 42 during the power stroke to minimize the fluid requirements of the operator, as hereinbefore described. So long as the switch is closed, solenoid valves will be actuated and power supplied to the operators 12 to hold the doors in an open position.

When the switch 70 is released, the solenoid valves 72, 74 are de-energized. However, the doors 10 cannot immediately begin to return to their closed position under the influence of spring 44 because one-way valves 38 and 43 are seated and bypass control valve 50 continues to close outlet port 64 .and to block the discharge of fluid from the cylinder 20 past the needle valves 42. In order to reduce the pressure in the line 66 sufiiciently to enable the bypass control valve 50 to return to its rest position against stop 58 under the influence of spring 56, the cylinder 20 of each power operator 12 is provided with a small pressure relief port 41 in the wall of the power cylinder 20 to provide communication from the interior thereof to the unpressurized reservoir within power operator 12.

The pressure relief port 41 is positioned at a longitudinal position in the wall of the cylinder 20 so that it cannot discharge pressurized fluid from the cylinder 20 until the piston 16 reaches the end of its power stroke (i.e., the position as shown in phantom lines). In this manner, it does not result in the loss of any hydraulic fluid during the power stroke, or the door opening movement of the hydraulic operator. Since the solenoid valves 72 and 74 are closed when the switch 70 is released, the small leakage of hydraulic fluid through the pressure relief port 41 of each power operator 12 serves to reduce the pressure of the hydraulic uid within the cylinder 20* to cause the unseating of one-way valve 38 to reduce the pressure within supply tube 34, manifold 40 and tube 66. With the pressure in tube 66 so reduced, the spool valve 54 is returned to its rest position against stop 58 under the bias of spring 56 and the three bypass needle valves 42 of the power cylinder 20 can then discharge the liquid trapped in the cylinder 20 so that the piston 16 can move to the right under the influence of spring 44 and the damping provided by the limited rate of discharge of the fluid past the needle valves 42 to return the door to its closed position. It will be understood that for left-hand operation a similar pressure relief port 41 may be provided for cylinder 22 to function in the same manner as port 41 does with respect to cylinder 20.

The time required for the pressure in tube 66 to be reduced su'iciently for the bypass control valve 50 may be adjusted by adjusting the size of the port 41. The time is preferably of the order of one to two seconds to cause the door to dwell briefly after the control switch 70` is opened, and this has been accomplished by the use of a port 41 having a diameter of about l5 mils.

It will be further observed that as the control switch 70 is opened, the power from the A.C. source to the motor relay 76 through rectifier 77 is also interrupted. However a significant feature of this invention is the provision of a suitable time delay 81 so that the power continues to be applied to the motor for a preselected period of time after control switch 70 is opened for the reason hereinafter more fully described.

In accordance with one aspect of this invention, the size and capacity 0f the positive displacement supply pump 80 selected for use in the system illustrated herein is less than that required to power the two doors 10, and in practice, it has been found that the use of a pump 80 having three-fourths the required capacity required in conventional systems results in satisfactory performance of the system.

In order to provide sutiicient additional power to operate the doors, there is provided in accordance with the invention, an automatically replenished accumulator, or reservoir of pressurized fluid 84, to aid the pump 80 during peak load periods of the power strokes of the operators (i.e., during the door opening movement). Another characteristic `of this design is that time delay means 81 is provided to operate the motor 78 over a sufciently long period of time at the end of each power stroke of the system to recharge the accumulator to its full preset pressure and to discharge a small amount of uid through the pressure regulating valve 86I back to the supply reservoir. However, -since the hydraulic fluid available for recirculation is quite limited in quantity, it will heat up quickly so that the time delay means 81 is preferably adjusted to minimize the amount of fluid recirculated through pressure regulating valve 86 during each door opening cycle but to assure that some fluid is recirculated.

Reference to FIG. 3 will indicate the conventional requirements for pressurized hydraulic fluid during the normal powered door opening movement of the doors 10. During the first portion A of the door opening movement, the pump 80, which begins to pump when the control switch 70 is closed to initiate each door opening movement, has sufficient capacity to provide all the needs of both operators 12 of the system simultaneously. Thereafter, and for a second portion B of the door opening movement, the fluid which has previously been stored under pressure in the accumulator 84, is required to -aid the pump 80' in supplying the required amount of fluid. Otherwise, the fixed output rate of the positive displacement pump 80l could not keep up with the fluid requirements of the operators 12, and the pressure in cylinders 20 would fall with the possible result that bypass control valve 50' would open and the doors would stop or oscillate slowly in a partially opened position. Thereafter, during the final portion C of the door opening movement, the pump 80 again has sufficient capacity to provide all the uid required to operate the doors and additionally to deliver a portion of its output to the accumulator to begin to recharge the accumulator. Finally, after the pedestrain leaves the doorway and control switch 70 opens, the pump motor '78 continues to be energized brieily because of the time delay provided by the time delay circuit 81 for a further suflicient period of time D to recharge the accumulator 84 to its full pressure and to recirculate a small quantity of fluid through the pressure regulating valve `86 so that the system is fully conditioned for the neXt operating cycle.

It is readily apparent that it is essential that the pressure in the accumulator be automatically and fully replenished during each cycle since, otherwise, the pressure of the system, after repeated cycles, may become insuficient to close bypass control valves 50. The result would be that the operators might not receive sufficient uid to open the doors. Moreover, since recirculating fluid through the pressure regulating valve 86 also rapidly heats the limited quantity of hydraulic iiuid in the system, the amount of uid recirculated must be minimized particularly under conditions of heavy use. Finally, the use of a bypass control valve 50 which minimizes the leakage during the power stroke while retaining the advantage of damped door closing by permitting the power piston to be used as a checking piston having bypass needle valves during the closing movement of the door, is particularly advantageous in the system.

While the invention has been described inconnection with an automatic operator system having doors installed in -a single doorway, it is readily apparent that it can also be be utlized with doors installed in separate doorways or with an operator system for a single door in which the pump capacity is less than that which is required for the pump stroke of the operator.

As will be rapparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is dened in the appended claim.

I claim:

An automatic door operator system including a hydraulic cylinder having a piston therein and source of pressurized hydraulic iluid for powering the piston to its open position in response to pedestrian traffic through the associated doorway, said source comprising a pump of limited output delivery rate relative to the requirements of the system and an auxiliary accumulator, power means for returning the `door to its closed position, conduit means for connecting said source to said cylinder including a one-way valve for Ipreventing reverse llow of hydraulic uid from said cylinder to said source bypass valve means in the cylinder through which trapped hydraulic fluid in the power cylinder is discharged to damp the operator during the return stroke of the piston, and a hydraulically operated bypass control valve responsive to the pressure of the hydraulic iiuid at the inlet of the power cylinder for preventing the discharge of hydraulic fluid through the bypass valve means during the power stroke, and a pressure relief -port in the wall of said hydraulic cylinder to reduce the pressure of the hydraulic uid at the inlet of said power cylinder, said piston being movable past said pressure relief port as the piston reaches the end of the power stroke -to place said port in communication with the pressurized iluid within the cylinder only when said piston reaches the end of the power stroke.

References Cited by the Examiner UNITED STATES PATENTS 3,067,993 12/1962 Stretton 49-30 3,084,927 4/1963 Linder 49-264 3,232,600 2/1966- Dimmitt et al. 49-138 REINALDO P. MACHADO, Primary Examiner.

I. K. BELL, Assistant Examiner. 

